Punch



June 28, 1938. M. L. ENGLER PUNCH Filed Nov. 21, 1936 INVENTOR Max L. E ler BY W 7 ATTORNEYS Patented June 28, 1938 UNITED STATES PATENT OFFICE PUNCH Max L. Engler, Akron, Ohio, assignor to The General Tire & Rubber Company, Akron, Ohio, a corporation of Ohio Application November 21, 1936, Serial No. 112,061

2 Claims. (Cl. 164-124) This invention relates to punch devices and body of the device in a heat insulating body i0. more particularly to punches for formingholes Electrical energy is supplied to the resistance in semi-plastic sheet material such as unvulwire 8 by the lead-in cord ll. canized rubber and the like. In operation, the cutting edge 2 of the punch An object of the present invention is to provide l, is caused to pass down substantially through a punch that is particularly adapted for conthe uncured side wall rubber [2 of the inner tube ventional practices in the manufacture of rubber while supported on the bench l3. The notch 3 inner tubes. in the cutting edge 2, leaves a connecting ribbon Another object is to provide a punch that M of the stock that anchors the cut-out slug 15 leaves the punched-out slug free of the punch to the material of the tube wall. The major 10 cutting blade and somewhat elevated above the portion of the slug I5 is drawn up out of, and material punched in order that the slug may be inclined to the plane of the tube wall I2 when the readily grasped and torn loose by the punch oppunch is lifted, as shown in Fig. 4. The slug [5 in erator. its elevated and inclined position is easily and With the above and other object in view, quickly grasped by a worker and the ribbon I4 which will be apparent to those familiar with broken to complete the operation. This avoids the art to which this invention pertains, an emthe use of complicated means for clearing the bodiment of the present invention is disclosed in punch cavity and is very convenient and useful in the accompanying drawing, wherein operation.

Figure l is an elevational View, shown partly It is to be understood that the particular emin section with parts broken away, of a punch bodiment of the invention that is shown and assembly that embodies the present invention; described herein is for the purposes of illustration Fig. 2 is an end view of the punch blade lookand explanation and that various modifications ing in the direction of the arrows 22 of Fig. 1; in the punch and in the contour of the punch Fig. 3 is an enlarged elevational view in section cutting blade and notch, and in the carrying and g of the punch blade in an operating position in supporting means, and in the punch heating the process of punching openings for valve stems means, may be made without departing from the in an uncured rubber tube wall; invention as defined in the appended claims.

Fig. 4 is an elevational section of a portion of What I claim is: the fiat stock subsequent to the withdrawal of l. A punch for forming holes in unvulcanized the punch blade shown in dot and dash lines; rubber compound in sheet form, comprising a and punch body having a tip terminating in a cutting Fig. 5 is a perspective of a portion of the edge formed by the intersection of an external punched fiat stock with the slug shown in dot cone-shaped face and an internal cylindrical and dash lines. bore, a notch of a fraction of the depth of the :15

In the accompanying drawing the punch 1 commaterial to be cut formed in said cutting edge, prises a punch body having a hollow centered, and means for heating said cutting edge, whereby frusto-conical cutting edge 2, that is interrupted the outer face of said cone-shaped tip pulls free by a notch 3. The punch l is mounted on a of said sheet material and said inside bore draws suitable carrying means, such as the thrust mema cut slug substantially out of its hole but leaves her 4 and the supporting arm 5 by the externally the slug connected at a single localized point threaded screw 6 that forms a part of the thrust of small cross sectional area. member 4 that is secured to the supporting arm 2. The method of punching holes in sheet 5 in conventional manner, as by the nut 1. material of uncured rubber compound which con- The punch I may be heated, if desired, as sists in severing a slug of rubber from the sheet when punching valve stem holes through the side entirely around one surface portion and around wall of uncured inner tube rubber and the like, the other surface portion except over a Very by an electrical resistance wire 8, that is wound small area from which the slug may readily be about the portion of the thrust member 4 that is torn loose and lifting the slug partially from the adjacent the punch I. The resistance wire 8 is material by engagement of the slug with the embedded in suitable insulating material 9 as punching device. well known to those skilled in the art. MAX L. ENGLER.

Thermal loss is minimized by enclosing the 

